Home / What insurers look for / Gaps over 1/8 inch
Do I need to seal gaps bigger than 1/8 inch?
No insurer list or state rule asks for it by that name. The 1/8 inch figure in the IBHS standard is the largest mesh opening allowed. San Diego lists sealing gaps over 1/8 inch as a voluntary step.
The state Zone 0 rule is not law yet. Insurers and IBHS already use their own lists.
What to check
Walk the outside and look at siding joints, damaged boards and trim.
Check where exposed rafter tails and blocking meet the wall.
Check the edges of the garage door.
Replace damaged siding boards instead of caulking over them.
What each list says
The lists do not always agree. Here is what each one says about this.
- IBHS Essential
1/8 inch is the largest opening allowed in vent mesh and under-deck mesh. With tested vents, joints are sealed as the maker instructs. On an existing deck, IBHS Enhanced requires a gap-free walking surface and gap-free stair treads and risers.
- State discount list and FAIR Plan
No item on gaps.
- San Diego
A voluntary step: caulk or plug gaps over 1/8 inch in siding, and around exposed rafters and blocking. Weather-strip gaps over 1/8 inch between garage doors and frames.
- State draft
The August 2026 draft, as we read it, sets no standard for this.
Sources
- IBHS Wildfire Prepared Home Technical Standard (2025 edition)
- Safer from Wildfires regulation: frequently asked questions, California Department of Insurance, September 2026
- Zone 0 guidelines for existing structures, City of San Diego, April 2026